Project Summary/Abstract This project is focused on accelerating the development and pre-clinical testing of new and effective approaches to therapy of hereditary retinal degenerations. These diseases are a major cause of blindness in people, affecting over 100,000 Americans, and are caused by a large number of different gene mutations, not all of which have yet been identified. Similar diseases also affect dogs, in many cases caused by identical or essentially similar gene mutations to those affecting people. In this project, studies will be undertaken in a research colony of dogs affected by such hereditary retinal diseases to better understand the genetic and pathogenetic mechanisms of these diseases, and evaluate potential methods of disease prevention, therapy or amelioration. Specific canine strains with well characterized retinal disorders will be maintained, bred, and made available to research investigators for collaborative studies aimed at a) increasing our understanding of the molecular mechanisms involved in these diseases and b) preclinical evaluation of potential therapies. Collaborations to effectively utilize these mutants will be initiated by the Principal Investigators interacting with independently funded investigators, to develop, implement and conduct specific protocols for optimal utilization of these mutants. Special emphasis will be placed on collaborative studies that: i) develop vectors for gene therapy that primarily target rod and/or cone photoreceptors, and test these vectors in appropriate canine models. For example, cone-specific vectors will be tested in canine models of achromatopsia, and rod-specific vectors will be tested in a canine model of autosomal dominant retinitis pigmentosa. ii) identify the causative mutations in new canine hereditary retinal degenerations, and investigate the cell biologic mechanisms critical to the pathogenesis of such diseases. For example, the mutations responsible for 3 canine cone-rod dystrophies will be identified. This will then allow these models to be used for gene-specific therapy studies. iii) Identify molecular signals favoring either the death or survival of photoreceptors during the onset of disease, and attempt to modulate such processes as either an adjunct or alternative to gene-specific therapies.